Removed unneccessary return
Introduce osgDB::PropetyInterface class that provided a generic interface for get/setting properties on scene graph objects, utilizing the osgDB serializers to do
the actual interface query and set/gets.
Added type maps to help with querrying supported type names
Added compoundClassName() convinience method to standardize the generation of the compoundClassName.
Added initial cut of white and black lists
Removed unnceccesary setNumChildrenRequiringUpdateTraversal from VolumeTile constructor.
Merge branch 'master' of https://github.com/openscenegraph/osg into Dev